Synthesis, Chracterization and Insecticidal Evaluation of Some p-tert-Butylthiacalix[4]arene Derivatives against Cowpea Aphid (Aphis craccivora Koch)

Cowpea (Vigna unguiculata) is one of the most important crops in semiarid areas of the world, where it thrives in hot, dry conditions. While cowpea is able to withstand abiotic stresses, it suffers serious losses from biotic antagonists, including infestation by the cowpea aphid (Aphis craccivora). Cowpea aphid infestations are highly destructive, especially on young plants. However, it is unclear whether cowpea aphid damage is the result of aphids having phytotoxic effects on their hosts, or simple density effects. To better understand cowpea aphid damage and the potential for resistance traits to mitigate aphid impacts, we evaluated phenotypic changes in cowpea in response to variable aphid densities and systemic versus local infestations. Low aphid densities induced leaf distortions and pseudogalling, suggesting that cowpea aphids are phytotoxic to cowpea. Resistance to the cowpea aphid has been previously identified in an African cowpea germplasm, and near isogenic lines (NILs) containing resistance quantitative trait loci (QTL) were generated in the California blackeye cultivar background. Using a series of performance assays, we determined that resistance conferred by the two QTL counteracts aphid phytotoxicity and severely limits aphid growth and fecundity. Using choice assays, a preference by cowpea aphids for the susceptible NIL was observed. Electrical penetration graph analysis revealed that the resistance phenotype includes weak surface level deterrence and strong phloem-based resistance that manifests during the sap ingestion phase. Our study provides evidence of phytotoxic traits in A. craccivora while identifying a viable means of counteracting aphid damage and reproductive potential through resistance.

Cowpea, Vigna unguiculata, is a crop that is essential to semiarid areas of the world like Sub-Sahara Africa. Cowpea is highly susceptible to cowpea aphid, Aphis craccivora, infestation that can lead to major yield losses. Aphids feed on their host plant by inserting their hypodermal needlelike flexible stylets into the plant to reach the phloem sap. During feeding, aphids secrete saliva, containing effector proteins, into the plant to disrupt plant immune responses and alter the physiology of the plant to their own advantage. Liquid chromatography tandem mass spectrometry (LC-MS/MS) was used to identify the salivary proteome of the cowpea aphid. About 150 candidate proteins were identified including diacetyl/L-xylulose reductase (DCXR), a novel enzyme previously unidentified in aphid saliva. DCXR is a member of short-chain dehydrogenases/reductases with dual enzymatic functions in carbohydrate and dicarbonyl metabolism. To assess whether cowpea aphid DCXR (AcDCXR) has similar functions, recombinant AcDCXR was purified and assayed enzymatically. For carbohydrate metabolism, the oxidation of xylitol to xylulose was tested. The dicarbonyl reaction involved the reduction of methylglyoxal, an α-β-dicarbonyl ketoaldehyde, known as an abiotic and biotic stress response molecule causing cytotoxicity at high concentrations. To assess whether cowpea aphids induce methylglyoxal in plants, we measured methylglyoxal levels in both cowpea and pea (Pisum sativum) plants and found them elevated transiently after aphid infestation. Agrobacterium-mediated transient overexpression of AcDCXR in pea resulted in an increase of cowpea aphid fecundity. Taken together, our results indicate that AcDCXR is an effector with a putative ability to generate additional sources of energy to the aphid and to alter plant defense responses. In addition, this work identified methylglyoxal as a potential novel aphid defense metabolite adding to the known repertoire of plant defenses against aphid pests.

Considering the importance of safe food, avoiding of excess pesticide application and pesticide pollution the present study was conducted. In this experiment totally four pesticides were tested against cowpea aphid Aphis craccivora under pot culture experiment at College of Agricultural Technology, Theni. Among the four acetamprid 20 SP (0.125g/ml) proved highly effective against Aphis craccivora compared to the rest of the pesticides with mortality of 98.75 per cent. In case of dosage wise acetamprid 20 SL (0.125g/ml) and imidacloprid17.8 SL(0.25ml/l)proved to be highly effective with mortality percentage of 98.33 and 86.66, respectively. Thus, it is concluded that all the studied pesticides, Acetamprid proved effective to control the cowpea aphids. How to view point the article : Gowtham, V., Dilipsundar, N., Balaji, K. and Karthikeyan, S. (2016). Study on the effectiveness of pesticides against cowpea aphid (Aphis craccivora) Koch. Internat. J. Plant Protec., 9(1) : 146-149.

From diverse or indole-3-carbaldehyde, certain unique indol-3-yl-4H-pyran derivatives were generated by condensing with different nucleophiles. IR, 1HNMR, and elemental studies have all confirmed their chemical structures. The green catalyst for the formation of indol-3-yl-4H-pyran derivatives is a zinc-linked amino acid complex [Zn(L-proline)2]. Furthermore, the environmental friendliness of this synthetic technique was investigated by assessing the reusability of the Zn(L-proline)2 complex over five consecutive cycles with no significant loss of catalytic activity. This novel process has showed substantial advantages in terms of safety, simplicity, stability, mild conditions, a short reaction time, excellent yields, and good purity without the use of organic solvents. The antibacterial properties of the compounds produced were investigated and discovered to be promising. To determine whether compounds are appropriate as possible insecticidal agents, the toxicological activity of the synthesized compounds against Cowpea aphid, Aphis craccivora, was tested using leaf dip bioassay technique toxicity studies performed in the laboratory. KEY WORDS: One pot synthesis, Zn(L-proline)2, Indole-3-carbaldehyde, Aqueous media, Microwave irradiation, Cowpea aphid, toxicological activity Bull. Chem. Soc. Ethiop. 2024, 38(4), 1077-1090. DOI: https://dx.doi.org/10.4314/bcse.v38i4.21

A research trial to exploit the importance of life cycle phases and predatory potential of Chrysoperla zastrowi sillemi (Esben- Peterson) on cowpea aphid, Aphis craccivora Koch was carried out under laboratory conditions during 2022-23. Predator grub emerged from the egg within 3.00±0.72 days with a hatching percentage of 89.54±2.58. The avg. duration of the first, second, third instar and total larval phase was 2.48±0.50, 3.44±0.50, 3.84±0.99 and 8.68±0.47 days, respectively. The avg. pre-pupal duration was 1.00±0.00 days and that of pupa was 8.26±01.32 days. The mean interval of oviposition was 24.7±5.15 days. Male and female adult longevity was 23.96±3.61 and 34.36±3.81days, respectively. The total life cycle was completed in 34.38±5.81 days. In the feeding potential study, the average daily consumption of aphids during the first, second and third larval instars were 9.28±0.45, 20.86±0.53 and 27.94±0.59 as well the average total number of aphids consumed was 31.20±4.04, 64.32±3.06 and 116.4±2.49, respectively. The total per day consumption of aphids and prey consumed in the entire larval duration was 58.08±0.89 and 211.6±6.4 number of aphids, respectively. According to the findings, the green lacewing, C. zastrowi sillemi, has a high chance of surviving on cowpea aphids at every stage and can be a great support to an organic pest management program, offering advantages all through the growing season.

The variegated ladybird beetle, Hippodamia variegata (Goeze) is one of the most important predator of cowpea aphid. In this study, the biological aspects of ladybird beetle, H. variegata feeding on cowpea aphid, Aphis craccivora Koch were investigated under laboratory condition. The average incubation period of H. variegata was 2.33±0.47 days and the duration of total larval period was 12.80±0.96 days. The pre-pupal and pupal periods were 1.06±0.25 and 3.43±0.50 days, respectively. The mean pre-oviposition period was 4.80±0.63 days and the oviposition period was 24.40±3.09 days. The female beetles laid on an average 374.70±22.41 eggs with the hatching per cent of 87.64±4.32. The mean longevity of the male and the female beetles were 27.96±1.21 and 30.93±0.98 days, respectively. Keywords: Variegated ladybird beetle, development, biology, life cycle, Hippodamia variegate, cowpea aphid, Aphis craccivora

Phytohormones function as signal molecules that regulate physiological processes to protect plants from environmental stresses, including aphids’ attack. We studied the pattern within the defense mechanisms of soybean [Glycine max (L.) Merr. cv. “Nam Dan”] regarding the signaling pathways of salicylic acid (SA), and jasmonic acid (JA) in response to cowpea aphid (Aphis craccivora Koch). With infestation by cowpea aphid, SA was the first to accumulate and reached high levels 24 hours post-infestation (hpi). An accumulation of SA in the early response of soybean probably triggers inducible specific defense reactions. Following SA, JA was later induced and continuously increased to high levels 96 hpi. An accumulation of JA in the later response may be a critical step in the signaling of the downstream defense cascade. In addition, phenylalanine ammonia-lyase (PAL, EC 4.3.1.24) and benzoic acid 2-hydroylase (BA2H), enzymes involved in the biosynthesis of SA, and lipoxygenase (LOX, EC 1.13.11.12), an important enzyme in the JA biosynthesis pathway, were also induced by cowpea aphid. The changes in the enzymatic activity of PAL, BA2H and LOX, and expression of gene encoding PAL were closely associated with the accumulation of endogenous SA and JA, respectively. The variations in the levels of these defense-related compounds were strongly connected with density and the duration of cowpea aphid infestation. Different accumulations of SA- and JA-signaling pathways may contribute to a coordinated regulation leading to the formation of resistant lines in the defense mechanisms of G. max cv. “Nam Dan” against A. craccivora.

Cowpea aphid (Aphis craccivora Koch) is a plant pest that causes serious damage to vegetable crops. Extensive use of synthetic chemical pesticides causes deleterious effects on consumers as well as the environment. Hence, the search for environmentally friendly insecticides in the management of cowpea aphids is required. The present work aims to investigate the aphicidal activity of pomelo seed oil (PSO) on cowpea aphids, the possible insecticidal mechanisms, its chemical constituent profile, as well as the toxicity of its primary compounds. The results of the toxicity assay showed that PSO had significant insecticidal activity against aphids with a 72-hour LC50 value of 0.09 μg/aphid and 3.96 mg/mL in the contact and residual toxicity assay, respectively. The enzymatic activity of both glutathione S-transferase (GST) and acetyl cholinesterase (AChE) significantly decreased, as well as the total protein content, after PSO treatment, which suggested that the reduction of AChE, GST, and the total protein content in aphids treated with PSO might be responsible for the mortality of A. craccivora. The GC-MS analysis revealed that PSO contained limonene (22.86%), (9Z,12Z)-9,12-octadecadienoic acid (20.21%), n-hexadecanoic acid (15.79%), (2E,4E)-2,4-decadienal (12.40%), and (2E,4Z)-2,4-decadienal (7.77%) as its five major compounds. Furthermore, (9Z,12Z)-9,12-octadecadienoic acid showed higher toxicity to aphids than both PSO and thiamethoxam (positive control). This study emphasized the potential of PSO as a natural plant-derived insecticide in controlling cowpea aphids and also provided a novel approach for the value-added utilization of pomelo seed.

Severe yellowing and stunting of plant growth was observed in experimental plots of Desmanthus virgatus (desmanthus) at the Tamworth Agricultural Institute during the 2015/16 summer season. Both symptomatic and non-symptomatic plants were tested for the presence of a range of viruses by Tissue blot immunoassay and symptomatic plants consistently reacted positive to Alfalfa mosaic virus (AMV), while non-symptomatic plants were negative to all viruses tested. AMV was not detected in seedlings grown from seed collected from AMV-positive desmanthus plants. AMV was readily transmitted from AMV-positive desmanthus plants by mechanical inoculation to faba bean, but attempts to transmit the virus from AMV-positive Medicago sativa (lucerne) plants to desmanthus by mechanical inoculation were unsuccessful. However, AMV was successfully transmitted from lucerne to desmanthus by Aphis craccivora (cowpea aphid). Aphid feeding studies showed that the cowpea aphid, but not Acyrthosiphon pisum (pea aphid), could colonise and multiply on desmanthus. AMV could become a limiting factor for the adoption of desmanthus as a pasture legume in NSW, particularly as AMV has been reported to be seed transmitted in desmanthus.

Resistance monitoring and enzyme activity in three field populations of cowpea aphid (Aphis craccivora) from Egypt

Cowpea aphid, Aphis craccivora Koch is one of the important pests of legumes. It is a cosmopolitan and polyphagous pest causing 30-35% damage to vegetable crops globally. Chemical control of this pest is not only expensive but also has deleterious effects on human health, environment and non-target organisms. Biological control is one of the most important components of integrated pest management to achieve eco-friendly and sustainable management of crop pests. Coccinellid predator, Coccinella transversalis Fab. is an efficient predator known for its appetite on cowpea aphid under vegetable ecosystem. With this background, we conducted a study on biology, morphometric and functional response of C. transversalis on cowpea aphid under laboratory conditions (27±1°C and 65±5% RH) at Biological Control Lab, ICAR-Indian Agricultural Research Institute, New Delhi, during 2016-17. Type of functional response was determined through polynomial logistic regression of proportion of prey consumption to the density of prey. Functional response parameters were obtained by fitting the data to the Holling's and Roger's equations. Total life span of male and female was ranged from 47-64 and 60-71 days, with a mean of 56±6.2 and 66±3.9 days, respectively. Both male and female of C. transversalis were found to exhibit Type II functional response. Female has showed high attack rate (1.99±0.141) compared to male (1.90±0.088) with maximum prey consumption of 84.41 and 80.51 aphids/day, respectively. Handling time obtained for males (0.0124 day) was higher than females (0.0118 day).

Glandular trichomes on the leaves of wild tomato, L. hirsutum f. hirsutum Mull, also known as Solanum habrochaites (Solanaceae), synthesize and accumulate high levels of methyl ketones (MKs). L. hirsutum accession LA 407, having high concentration of MKs, was grown from seeds under greenhouse conditions. Four MKs (2-undecanone, 2-dodecanone, 2-tridecanone, and 2-pentadecanone) were screened for their toxicity to spider mites, Tetranychus urticae Koch and cowpea aphids, Aphis craccivora Koch. The objectives of this investigation were to: (1) develop a bioassay for testing MKs on spider mite and cowpea aphid mortality and (2) compare the efficacies of wild tomato leaf crude extracts and pure standard materials of MKs against spider mite and cowpea aphid mortality. Our results revealed that spider mites are most sensitive to 2-tridecanone (LC50 = 0.08 μmole cm−2 of treated leaf surface) and least sensitive to 2-undecanone (LC50 = 1.5 μmole cm−2 of treated leaf surface) 4 h after treatment. Similarly, 2-tridecanone caused greatest mortality (LC50 = 0.2 μmole cm−2 of treated leaf surface), whereas 2-undecanone caused the lowest morality (LC50 = 0.48 μmole cm−2 of treated surface) of cowpea aphid. We concluded that all MKs tested in this investigation are toxic to spider mites and aphids. 2-Tridecanone is more effective in killing mites and aphids compared to other MKs. Toxicity of crude extracts, prepared from the leaves of L. hirsutum accession LA 407, to spider mites and cowpea aphids revealed greater mortality compared to a combined mixture of MKs standard material (used at the same concentration as found on LA 407 leaves). This indicates that in addition to MKs, other unidentified compounds in LA 407 leaf extract also have pesticidal properties. Accordingly, leaf extracts of LA 407 could be explored in crop protection, and they might open a new area of MK formulations and discovery of biorational alternatives for pest control in agricultural fields.

Aphis craccivora Koch (Hemiptera: Aphididae), known as the cowpea aphid, is a polyphagous pest that causes severe damage throughout the phenological cycle of several economically important crops. For the control of this hemiptera, as for most agricultural pests, the chemical method has been the most used. Considering the Integrated Pest Management - IPM, the use of plant extracts is an option that has been widely considered. Thus, this study aimed to evaluate the bioactivity of aqueous extracts of Annona glabra, A. hypoglauca, A. montana and A. squamosa leaves, obtained in the Amazonian Savanna of Roraima, Brazil, on A. craccivora under laboratory conditions. Regarding the biological aspects on the cowpea aphid, the toxicity and repellency were evaluated with and without chance of choice. It was verified that the aqueous extracts of the four species of the genus Annona cause mortality in both nymphal and adult stages of A. craccivora, besides presenting repellent effect for this aphid. Because the aqueous extracts of leaves of the studied species present promising effects against A. craccivora, additional field studies of bioactivity of these Annona species on the black aphid, as well as their activity on beneficial and non-target organisms are suggested.

In order to explore the relationship between the structure and the toxicity to honey bees of seven-membered aza-bridged neonicotinoids, 16 novel seven-membered aza-bridged neonicotinoid analogues are synthesized by replacing the pyridine ring, and changing the substituents on the pyridine ring, the electron-withdrawing group NO2 and the imidazole ring of our previously developed aza-bridged neonicotinoid 1-[(6-chloropyridin-3-yl)methyl)]-10-(2,5-dimethylphenyl)-9-nitro-2,3,5,6,7,8-hexahydro-1 H-5,8-epiminoimidazo azepine (C-29). The insecticidal bioactivities against cowpea aphid ( Aphis craccivora) and the bee toxicities of these compounds are tested. Some of the title compounds present good insecticidal activities against cowpea aphid. The results also show that some of the title compounds exhibit lower bee toxicity than that of C-29 and imidacloprid. This suggests that changing the substituents on the neonicotinoids can influence the toxicity toward honey bees of these analogues.

In this study, the insecticidal activity against Cowpea aphids (Aphis craccivora) of a series of 23 phenylazo, pyrrole-, dihydropyrrole-fused and chain-opening nitromethyleneneonicotinoids was evaluated by using the multiple linear regression (MLR) and pharmacophore modelling. Conformer insecticide ensembles were modeled using the MMFF94s force field. Minimum energy conformers were employed to calculate structural parameters, which were related to the experimental pLC50 values. Several statistical criteria of goodness of fit and predictivity were checked to validate the models. Robust and predictable MLR models were obtained. Further, the Phase module from Schrodinger suite was engaged in the generation of the ligand-based pharmacophore models. The atom-based 3D-QSAR module from the aforementioned software was used for the validation of a best four-point pharmacophore model. The obtained significant statistical parameters attested thepharmacophore model validity. The MLR and pharmacophore models are useful for the prediction of new insecticides with activity against Cowpea aphids.